The major difference between the logs is in the way the data getdivided up into packets. In both the successful logs, there are sequences of bulk-OUT packets with lengths like:

44, 1, 15, 1, 13

where the unsuccessful transfer just has a single packet of length 74. Also, the successful transfers show a lot of bulk-IN traffic where the unsuccessful transfer doesn't have any. I don't know if that is relevant, however.